The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Conventional polymeric solar collectors typically include two manifolds that are each hermetically enjoined to each end of an absorber construction wherein the absorber construction is comprised of a great multiplicity of hollow conduits through which water is uniformly passed from one enjoined manifold to the other. The manufacturing of these solar collectors utilizes a variety of thermoplastic melt forming and enjoining methods that are in practice leveraged to significantly varying degrees in the quest for overall manufactured product value. Accordingly, polymeric forming manufacturability through extrusion has utilized 3 basic forms of solar collector absorber component construction. They are in order of manufacturability from the least leveraged to the most leveraged: (1) a single conduit preferably round, (2) a profile consisting of two parallel sheets with a multiplicity of connected partitions, (3) a string of planar aligned conduits, preferably round, with connective webs between each conduit and an attachment means at the end of each string.
Conventional methods for cost effectively joining the extruded absorber constructions to the manifolds in order of the least leveraged to the most leveraged include, (1) plastic thermal fusion via hot platen or infrared fixture welding to a separately extruded manifold, and (2) injection molding the manifold directly over the separately extruded absorber construction.
The most preferred embodiment of this present invention is directed toward the most leveraged methods of extrusion absorber construction and manifold joining or more specifically the over molding of manifolds directly over mold cavity inserted connectively spaced tube substrates. It features a novel molding apparatus and the further use of polypropylene as the primary core material of overall construction, and further uses very specific material formulation and process methodology to most effectively leverage the overall benefits of the novel apparatus. This present invention represents a giant step forward to a field of art that has been relatively stale, as shown by a brief summary of representative patent documents provided herein for reference.
U.S. Pat. No. 4,352,772, to Bezner describes what amounts to a very generalized insert or over molding method and a more specific apparatus oriented method to make a polymeric thermoplastic manifold to absorber joint of a solar collector more specifically or heat exchanger more generally. The document describes a “stay with the mold absorber tube supporting projection means”. All 3 of the previously mentioned extruded absorber embodiments are featured. Most particularly a connectively spaced tube absorber extrusion is featured in what as will here be revealed as a clearly non-viable embodiment as relating to the methods as disclosed. This as would be regarded as the most leveraged extrusion embodiment of the Bezner disclosure appears to limit its focus upon a concern that limited extrusion process accuracy, more specifically in the form of accumulated spacing error, must be compensated for to insure that the multiplicity of tubes will fit the extended uniform spacing of the very necessary supportive projections. This “elastic web” coping mechanism has been repeatedly shown to be unnecessary. It can be further shown that it is not even a viable manufacturing alternate. In particular, the very numerous overly sharp crevices within the outer shape contour of the extruded structure are exceedingly difficult to hermetically fill and fuse into during molding. It is of great significance that the ultimate assignee of the patent has over these past 3 decades has been manufacturing and marketing only the least leveraged extruded single tube absorber embodiment and not the “elastic web” coping mechanism.
Of additional practical significance is that the Bezner assignee has consistently over molded manifolds in only one foot wide sections. The pool heating market demands 4 foot wide solar collector constructions. To meet this demand the assignee has consistently built out 4 one foot wide completed sections fixture welded together in 6 places. The disclosure is totally silent as regarding the highly influential processing aspect of mold gating strategy. When one studies the product it becomes evident that it is molded through multiple gates that are located on the side of the manifold directly opposite the inserted absorber. This explains the one foot wide sections. It is known to this inventor that the manifold mold core will bend during injection more and more as the manifold width is progressively widened using such a mold gating strategy. This introduces undesirable manifold thickness eccentricity resulting in manifold warp and weakened manifold to absorber enjoinment. The true practical utility of the method as disclosed is arguably very limited to solar collector construction in accordance to its very particular and ongoing method of practice.
U.S. Pat. No. 6,787,116, to Williams et al. describes, essentially a “stay with the part separately molded polymeric insert” intended to provide a secondary seal in addition to the primary seal of the very general Bezner molded manifold over absorber method. The key patent eligibility aspect lies with the 4 sided hollowed out box like structure that is provided creating a perimeter around strings of inserted absorber tubes by means of a separately molded component having sufficiently thinned side walls to enable the heat delivered by the injected over molding material to overwhelmingly thermally melt and fuse with that separately molded insert.
Although adequate for their intended purposes, none of the above patent documents describe a primary header to absorber joint over molding process that employs a removable absorber tube support means. More particularly, there are inherent and unique benefits available with using connectively spaced tube mold cavity inserted substrates that can be more or less effectively integrated within the manufactured article relative to the extent to which the process methodology is developmentally leveraged. The assignee of this present invention has for many years been using such an apparatus with much room for significant improvement. In light of the above, it would be beneficial to introduce a novel removable absorber tube support means apparatus that is much more functionally developed than its foundational precursor, and is especially more functionally developed for molding manifolds over connectively spaced tube absorber extrusion constructions.